1. Field of the Invention
The invention relates to the provision of thermal protection inside combustion chambers, especially those in turbomachines such as turbojet engines, and in particular it relates to the fixing of thermal protection tiles placed inside such combustion chambers.
The power developed by a turbomachine is directly related to the temperature of the gases entering the turbine. To increase the power of such turbomachines, manufacturers have therfore created combustion chambers capable of generating very high output temperatures, for example close to or even exceeding 1,500.degree. C. for military turbojet engines and 1,350.degree. C. for civil turbojet engines. Moreover, the fuel consumption of such engines is very high at these operating temperatures. However, it decreases as the compression ratio increases, and modern turbojet engines therefore tend to have a higher compression ratio.
These and other considerations have thus led to turbojet engine designers to seek to improve the thermal protection of the walls constituting the combustion chambers, with the aim of lengthening the life of the chambers.
2. Summary of the Prior Art
One of the solutions devised to protect the walls of combustion chambers involves fitting them with a second wall on the inside thereof. This second wall is placed at a distance from the outer wall so as to create an annular space for the flow of cooling air drawn from outside the chamber. Examples of this solution are disclosed in GB Patent 2173891 and U.S. Pat. No. 4,302,941. To permit repair of this type of chamber, the second wall exposed to the full heat of the chamber is constituted by juxtaposed elements, commonly called "tiles", which are held slightly spaced from the outer wall, for example by means of spikes.
In the majority of cases, these tiles are fixed in a permanent manner. Consequently, dismantling is either very difficult or impossible. Moreover, assembly itself is not always easy.
It is an object of the invention therefore to provide a tile fixing arrangement which avoids these drawbacks.